Well head assembly with means for effecting a preloaded seal



March 28, 1967 E. K. PIERCE, JR 3,311,168

WELL HEAD ASSEMBLY WITH MEANS FOR EFFECTING A PRELOADED SEAL Filed Dec.4, 1964 3 Sheets-Sheet 1 INVENTOR 1 waapfl BAT/76E MY ZM Wiw ATTORNEY5March 28, 1967 PlERCE, JR 3,311,168

WELL HEAD ASSEMBLY WITH MEANS FOR EFFECTING A PRELOADED SEAL Filed Dec.4, 1964 5 Sheets-Sheet 2 Egg? A230 A50 ZNVENTOR Z2 WOOD/K BERCE RNEYSMarch 28, 1967 K, PIERCE, JR 3,311,168

WELL HEAD ASSEMBLY WITH MEANS FOR EFFEGTING A PRELOADED SEAL Filed Dec.4, 1964 5 Sheets-Sheet s INVENTOR ai 4M, wi 1 /W United States. Patent()fiice 3,311,1fl8 Patented Mar. 28, 1967 3,311,168 WELL HEAD ASSEMBLYWITH MEANS FOR EFFECTING A PRELOADED SEAL Elwood K. Pierce, J12,Houston, Tex., assignor to Gray Tool Company, Houston, Tex., acorporation of Texas Filed Dec. 4, 1964, Ser. No. 416,072 19 Claims.(Cl. 166-89) The present invention relates to well head equipment andmore particularly to a compact well head assembly including means foreffecting a preloaded seal in a casing head throughbore.

In the drilling of petroleum wells, it has been the usual practice tobeing drilling a relatively large diameter hole, then as drillingprogresses deeper to effect several reductions in the diameter of thewell being drilled. Usually each stage of the hole must be lined withcasing after it is drilled and cement run into the annulus between theexterior of the casing and the periphery of the hole. The casing sealsoff the hole from cave-ins, and the cement besides protecting the casingfrom corrosion, prevents migration of fluids from one formation toanother and allows the oil and/or gas produced by the well uponcompletion to be segregated. The cement additionally aids in retainingthe casing properly positioned with respect to the hole.

Usually, each casing extends upwardly to the surface of the well, eachsmaller casing being received within the casing set just before it.

In a conventional completion, the largest diameter outer casing usuallycalled a surface casing receives at its upper end a casing head whichhas an internal, generally vertically extending throughbore. Means suchas an upwardly facing tapered annular shoulder is usually provided inthe casing head throughbore for receiving and supporting a casinghanger.

Accordingly, after the well has been deepened sufficiently to receive asecond casing, of smaller diameter than the surface casing it is runinto the well and a hanger secured to its exterior near the upper endthereof. The hanger may take several forms such as those commonlyreferred to as boll-weevils, slip-type or Wrap-around type. Each have incommon provisions for gripping the exterior of the casing and seating ona shoulder or similar means provided in the casing head throughbore.

Often, means such as hold down wedges are provided in lateral ports inthe casing head for wedging contact with the upper end of the casinghanger or the hung casing itself in order to prevent upward movement ofthe casing if down hole pressure should at any time suddenly increase.

Alternative provisions for holding down a casing include providing anupwardly, inwardly tapering annular surface on the casing hanger abovethe region thereof which seats on the casing head throughbore shoulderor the like. Such a double tapered hanger is exemplified in FIGURE 9 ofthe United States patent Mueller, 2,162,- 179 granted June 13, 1939.

The double-tapered casing hanger upwardly converging surface is adaptedto be received against a complementarily curved surface at the lowerextent of the throughbore of a second casing head or a tubing head whichin a conventional well completion is supported on the first casing head.The two heads are secured to one another in some instances by boltsextending through radially outwardly directed flanges on each head, orby alternative means such as an expansible contractile segmented clampsecured over these flanges.

Drilling of the next smaller diameter segment of the hole is thenconducted through the second mentioned casing head or tubing head, carebeing taken to prevent damage to the throughbore of this head by thedrill string, drill collars or the like.

Conventionally, when the last-mentioned segment of the hole has beencompleted a casing is run into the Well through the throughbore of thelast-mentioned head and seated and held down with respect thereto bymeans similar to those discussed in regard to the first casing head.

This procedure is repeated for each succeeding casing. The casingsusually each being cemented in place just after being run into the wellas above-mentioned. Such wells are completed by a tubing head and tubinghangers which receive one or a plurality of strings of tubing whoselower regions are adapted to receive oil and/or gas from one or aplurality of producing zones in the well.

In order to prevent damage or undue danger to life and property, at eachstage during the completion of the well until it is finally completed,it has become the standard practice and often a requirement to provideblowout prevention devices at the well head. These devices in their morecomprehensive form include a plurality of blowout preventers secured ina vertically stacked relationship to whichever well head element istopmost at that particular point in the completion procedure.

As again exemplified by the Mueller Patent No. 2,162,- 179, inasmuch aseach successively upper casing head or tubing head conventionally has athroughbore which is reduced in diameter from that of the head on whichit is mounted in order to provide a hanger seat therein, the upperflange of each head is usually of smaller diameter than the lower flangeof the same head. This reduction in size is not merely a matter ofchoice or design, but one of necessity in the past in order to present aminimum of potential area for leakage to the fluid pressure with in thevarious conduits extending into the well. Characteristically, suchpressures actually or potentially increase as the depth of the wellincreases. A typical blowout preventer stack, beside a master drillingvalve characteristically includes a ram type preventer with blind ramsfor rapidly closing off exterior communication to the well at a timewhen no conduits or drill string extend through the stack and a ram typepreventer with pipe rams for rapidly closing off exterior communicationto the Well when casing, drill string or the like extend through thestack. The pipe rams when closed about a pipe prevent its upwardmovement when the pipe is subjected to a sudden increase in pressurefrom below. The two ram type preventers may be surmounted by a thirdpreventer having an annularly contractile ram element which is useful inclamping against pipe as well as against wire lines and the like.

Because of the progressive reduction in size of the succeeding casingand tubing heads upon which the blowout preventer stack is to bemounted, it has been necessary in the past to provide a plurality ofsuch stacks or at least a plurality of adapter hubs each of a size formounting on the particular Well head element which was topmost at aparticular stage of the completion of the well.

Usually the preventers of larger bore are rated for use at lowerpressures and those of smaller bore for use at higher pressures so thateven the use of adapters does not provide a complete solution to theduplication problem.

While the cost of such duplication of equipment and provision of specialadaptors was tolerable in many instances in the past, it has becomeincreasingly unjustifiable with the rise of drilling cost, theincreasing depth of petroleum wells and especially with the advent ofvery large diameter casing. For instance, the cost of keeping on hand afirst preventer stack for use on a 20 inch 0D. surface casing and asecond stack for use on the 13% inch O.D. casing next run into the holewould be too excessive to be economically feasible in many instances.

It should also be apparent that in the conventional procedure asoutlined even though other hold down means are provided before apreventer stack is removed preparatory to mounting a subsequent head onthe one on which the preventers had been mounted, there is lesscertainty that a blowout could be prevented in the hiatus or that 'if ablowout occurred at this time the pipe could be stri ped back into thehole.

It has been proposed in the prior art to alleviate some of thesedisadvantages, particularly as they relate to underwater completions byproviding a well head assembly where a casing having a relatively wideshoulder in its bore receives a hanger supporting a first casing andeach succeeding string of conduit is hangingly supported on successivelysmaller hangers which nest with and are supported upon thefirst-mentioned hanger. While such an arrangement is acceptable wherethe total weight of conduit to be supported by the head is not great,the increase in the CD. of the head which such a constructionnecessitates when the supported weight is very great, for instance fordeep wells, makes such an arrangement often unacceptable. As an examplethe resultant first casing hanger may have so large an CD. that it willnot fit through the available blowout preventers, so that the stack mustbe removed in order to place the first casing hanger. On the other hand,if the hanger seat in the casing head is made more narrow than wouldotherwise be considered prudent, in order to reduce the OD. of thecasing head to reasonable size, and the well later pushed to greaterdepth than had at first been contemplated, it is clearly apparent thatbearing failure of the single casing hanger seat could easily occur withresultant loss of'conduit into the well.

Another unitary head arrangement of the prior art contemplates theprovision of a plurality of vertically spaced seats within the headthrough bore, each for supporting a hanger and a string of conduitsecured to the hanger. A disadvantage of such arrangements is that theyare often little more compact than stacked individual heads and hangersand they are often more expensive because they involve large castings orforgings and are often not standard stocked items.

It is an important object of the present invention to provide a wellhead assembly which includes a casing head adapted to receive aplurality of hangers, supporting a portion of the weight of the hangersand casing suspended therefrom on a primary seat while transferring apredeterminable portion of the stress ensuing from the hanger and casingweight to the head at at least one region thereon above the primaryseat.

A further object of the invention is the provision of a well headassembly which partakes of the advantages of deep bowl and multi-seatunitary heads while minimizing their disadvantages.

Another object of the invention is the provision in a compact well headassembly of a casing head having a primary seat and a pair ofdifferentially tapered sealing surfaces spaced above the primary seatand above and below a side port and a hanger having complementarysealing surfaces and a seat for mounting the hanger in said casing, thesealing surfaces being spaced from one another and the seat by an amountsuch that the uppermost seal begins to set before the lower seal andbefore the hanger has seated in the head thus providing prestressedseals both above and below said side port and making provision fortransfer to the casing head, at points thereon above said seat, of atleast a portion of the stress of well head parts subsequently mounted onsaid hanger.

These and other objects of the invention as well as the principles andscope thereof will become more clearly apparent during the course of thefollowing detailed dlS- cussion relating to three exemplary embodimentsof apparatus according to the invention, the embodiments beingillustrated in the attached drawings.

In the drawings:

FIGURE 1 is a fragmentary longitudinal sectional view with portions inelevation, of a well head embodying principles of the present invention;

FIGURE 2 is a fragmentary elevation view of a second well head embodyingprinciples of the present invention, portions being broken away toexpose details otherwise hidden; and

FIGURE 3 is a fragmentary elevation view similar to FIGURE 2, of a thirdembodiment of the invention.

As shown in FIGURE 1, the well head assembly 10 includes a surfacecasing 12 secured to the well by means of conventional cement 14. Thesurface casing 12 is secured at its upper end to the lower end of acasing head 16, for instance by exterior threads 18 on the casing 12adjacent its upper end and interior threads 20 in the longitudinalthroughbore 22 of the casing head 16 adjacent the lower end thereof. Inthis manner, the head 16 is supported by the casing 12. Of course, thethreaded joint 18, 20 is exemplary and could be replaced by equivalentmeans such as a slip-on joint welded in situ to the surface casing.

The casing head 16 proceeding from the upper end 24 of the throughbore22 includes a first upwardly facing, tapered annular sealing surface 26,an annulus port 28 intersecting a cylindrically tapered region 30 of thebore just below the surface 26 and a second upwardly facing, taperedannular sealing surface 32 having a shallower taper angle with respectto a horizontal plane than the surface 26. The second sealing surface 32at its upper extent joins the surface 30 below the annulus port 28.

A cylindrically curved surface 34 extends downwardly from the lower,inner extent of the surface 32 and terminates in a counterbore 36.

Besides being intersected by an annulus port 28, or a plurality of suchports 28 angularly spaced from one another, the throughbore 22 is shownalso being intersected by a plurality of locking screw receiving,angularly spaced lateral ports 38 (only one being shown).

The port 38 isshown extending through the upper radial flange 40 of thehead 16. A plurality of angularly spaced, radially extending wedgeelement receiving ports 42 (one being shown) intersect the bore 22intermediate the upper -and lower extent of the surface 34. At least oneradial outlet 44 intersects the counterbore 36.

The locking screw 46 is shown having a frusto-conical head 48, athreaded body 50 engaged in the threaded bore 38 and a stem 52 havingwrench receiving means for effecting an advancement and retraction ofthe locking screw 46. The annulus port 28 is shown terminating at itsouter extent in a boss 54 peripherally surrounding the port. In usesuitable piping and valving may be secured to the boss 54 byconventional means such as bolts received in threaded sockets (notshown) in the boss, welding, or a threaded coupling. 7

The wedge 56 received in the port 42 is preferably of the non-rotatingtype having an eccentrically mounted drive stem 58, as disclosed in thecommonly assigned, copending application of Pierce, Ser. No. 260,372,filed Feb. 25, 1963, now Patent No. 3,248,132. The outlet 44 may beconnected to suitable piping and valving similarly to the port 28.

After the casing head 16 has been secured to the surface casing 12,drilling operations may be conducted through the bore 22 and the casingthroughbore 60. A convention-a1 blowout preventer stack (not shown) maybe secured to the casing head 16 upper flange 40 as by bolts eitherbefore or after the casing head 16 is mounted on the surface casing 12.

It is of interest to note that because the locking screws 46 and wedges56 are retractable, drilling operations con ducted through the bore 22have the advantage of the full bore, which would not be the case werethe bore choked with a large annular hanger seat.

When the hole has been drilled sufliciently deep to receive theintermediate casing 62, the latter is lowered into the well, the upperend of the casing 62 being secured to a hanger 64. The casing 62 isshown secured to the hanger 64 by exterior threads 66 adjacent the upperextent of the casing and interior threads 68 adjacent the lower extentof the throughbore 70 of the hanger. Conventional alternative securementsuch as by welding could be utilized. As shown the hanger throughbore 70is also interiorly threaded at 72 intermediate the ends thereof toremovably receive a lowering nipple, test plug or the like.

Adjacent and leading to the upper end of the hanger 64, an upwardlyfacing tapered annular seat 74 is formed having a taper angle of, forinstance, 15 degrees with respect to a vertical plane. The exterior ofthe hanger 64 is preferably tapered adjacent its upper end at 76providing an upwardly facing tapered annular surface for engagement bythe frustoconical locking screw heads 48. Adjacent and proceedingupwardly from its lower end the hanger 64 is circumferentially relievedto form a downwardly facing annular seat 78. A laterally extendingopening 80 is formed through the hanger for communication with the port28. Above and below the opening 80 sealing surfaces 82 and 84 havingtaper angles complementary with the differentially tapered sealingsurfaces 26 and 32 are formed. Convention-a1 compressible, moldedannular rings 86 of sealing material are shown received in annularrecesses 88 in the surfaces 82, 84.

Using a conventional lowering bushing or the like the hanger 64 islowered through the preventer stack toward the position shown, thescrews 46 being retracted and the wedges 56 extended into the bore 22 asshown to provide a primary hanger seat. Because of the differentialtaper and spacing of the sealing surfaces 26, 82 and 32, 84, the morenearly vertical surface 82 begins toland at 26 substantially before theshoulder 78' contacts the wedges 56, shortly thereafter but still beforethe shoulder 78 contacts the wedges 56, the sealing surface 84 begins toland at 32.

By way of example, in an instance where the casing head bore 22 has a13% inch ID. and is received on a casing 12 of 16 inch O.D., the largestCD. of the hanger 64 for hanging a 10% inch O.D. casing 62 is 13 /2 inchsince the seat is provided by the retractable wedges 56.

While drilling for and running the 10% inch O.D. casing, the wedges 56are retracted leaving 13% inch diameter bore 22 substantially fully openas above noted. The wedges 56 when run in choke the bore 22 to provide ashelf-like seat for the 10% inch O.D. casing 62.

In the example, the surfaces 26, 82 have a inch taper per foot (a 16:1ratio vertical to lateral) and the surfaces 32, 84 a 2 inch taper perfoot (a 6:1 ratio vertical to lateral). Accordingly, the seal 26, 82begins to set when the casing hanger shoulder 78 is /2 inch to inchabove the upper horizontal surface 90 of the Wedge 56 and the seal 32,84 begins to set when the casing hanger shoulder 78 is about inch abovethe surface 90. By the time the shoulder 78 seats on the surface 90 therings 88 have been compressed so that they are flush with the surfaces82, 84 and the seals 82, 26 and 84, 32 are preloaded so as to carry apredeterminable proportion of the casing hanger 64 load directly to thehead 16 adjacent the surfaces 26 and 32. It is important to note thatthis preloading additionally provides a greater assurance againstleakage about the annulus port 26, 80 than would be the case if theseals were not preloaded.

After the casing 62 has been run and the hanger 64 seated, the lockingscrews 46 may be run in so that the heads 48 engage the surface 76 tohold down the hanger 64 and casing 62. The casing 62 may beconventionally cemented by pumping cement down the bore 92 of the casing62 around its lower end and up the annulus between the casings 62 and12. The cement forces the drilling fluid ahead of it upwardly and outthrough the outlet 44. When the cement has set, the drill string can belowered through the preventer stack, into the casing 62, bore 92, thewiper plug, if used, drilled through and drilling operationsrecommenced. Upon reaching the desired depth, the drill string can bepulled and the oil string 94 of easing run into the well and hung forinstance utilizing a double tapered hanger 96 of the type disclosed inthe commonly assigned U.S. patents to Mueller et al., No. 2,620,880,granted Dec. 9, 1952; Mueller et al., No. 2,624,413, granted Jan. 6,1953; Watts et al., No. 2,751,- 235, granted June 19, 1956; Watts etal., No. 2,754,134, granted July 10, 1956; or Phillips, No. 2,754,136,also granted July 10, 1956. As shown the hanger 96 has a lower,downwardly facing tapered annular surface 98 which includes acompressible ring 100 mounted in an annular recess 102 thereof and seatsagainst the surface 74 of the hanger 64 so that .a substantial portionof the load of the hanger 96 and casing 94 is transmitted through thehanger 64 adjacent the surface 74 and to the casing head 16 adjacent thesurface 26. Some additional proportion of the loading is transmittedthrough the hanger 64 at 84 to the head 16 and the only remainingportion is incumbent upon the wedges 56.

The hanger 96 is temporarily sealed to the casing 94 by the resilientseal 104 as disclosed in the last-mentioned patents and permanentlysealed thereto by the deposition of welding material as at 106. Holddown means such as additional locking screws (not shown) may be providedto hold the casing 94 and hanger 96 down while the preventer stack isremoved. An upper, upwardly facing tapered annular shoulder 108 providedonthe hanger seals against a complementary surface 110 on a conventionaltubing head 112. The tubing head 112 is shown having a lower radiallyextending flange 114 which is bolted as by bolts 116 to the flange 40 ofthe casing head 16 in order to secure the tubing head 112 in place andhold down the hanger 96. An API ring 118 is shown received incomplementary annular recesses 120 in the upper and lower ends of thecasing head 16 and tubing head 112 respectively to seal between thesemembers. Alternately opposed flexible tapered lip hard metal sealingrings such as are disclosed in the commonly assigned U.S. patents'toWatts et al., 2,766,829, 2,766,998, and 2,766,999, all granted Oct. 16,1956, and using clamping arrangements as shown in those patents in placeof the bolted flanges 40, 114, 116. The Well may then be conventionallycompleted with tubing, tubing hangers, Christmas tree cap, Christmastree and perforated, packed off, and otherwise completed as desired.

The embodiments shown in FIGURES 2 and 3 are intended to illustrate thebroad range of applicability of the principles of the present invention.

In FIGURE 2, a first casing head 120, having a longitudinal throughbore122 is shown received via a welded slip on joint at 124 on a surfacecasing 126. The next smaller diameter casing 128 is shown supported inthe head 120 by a split hanger 130 of the type generally shown in theU.S. patent to Watts et al., No. 3,051,513, granted Aug. 28, 1964, andmore particularly as shown in the commonly assigned copendingapplication of Watts et al., Ser. No. 65,064,'filed Oct. 26, 1960, nowPatent No. 3,257,130. As more completely described in the just-mentionedpatent and application, the hanger 130 comprises a lower hanger element132 preferably formed from a plurality of sets of arcuate segments 134,136 and a bonnet 138. Each segment set 134, 136 is interdigitated andthe segments 134 and 136 are arcuately movable with respect to oneanother between a first position wherein they are arcuately coterminousand the segment sets can be individually inserted in the casing head anda second position wherein each upper segment 134 extends arcuatelybeyond the lower segment on which it is carried in its first positionand is interdigitated with an adjacent lower segment to form an annularhanger element 132. The slips 140 of the hanger element 132 grip andsupport the casing 128 and the element 132 is in turn supported on theupwardly facing tapered annular load shoulder 142 in the bore 122.

As explained in the aforementioned Watts et a1. application, the bonnet138 first provides temporary sealing at 144, then permanent sealing byvirtue of the deposition of welding material at 146. The downwardlyfacing ,frusto-conic sealing and seating surface 148 on the bonnet 138is received on the upwardly facing tapered annular shoulder and sealingsurface 150 formed in the bore 122 adjacent and leading to the upperextent thereof.

, The welding material 146 may be deposited in such a manner forinstance while holding the casing 128 in tension, that when positionedas shown, a portion of the weight of the casing 128 is carried throughthe weld to the bonnet 138 and through the seat 148 into the casing head120.

The bonnet 138 has an upwardly facing tapered annular sealing surface152 sealingly received against a downwardly facing tapered annularsealing surface 154 formed in the throughbore 156 of a second casinghead 158- received on'the casing head 120 and secured thereto as bybolted flanges 168 as shown sealed by an API ring 162. Alternatesecurement and sealing such as the opposed, defiectable, hard metaltapered lip annular sealing rings and clamps as shown in theaforementioned patents to Watts et al., 2,766,829, 2,766,998 and2,766,999 may be employed.

The engagement of the surfaces 154 and v152 additionally serves to holddown the bonnet 138 and conduit 128.

Above the annulus port 164, the bore 156 is enlarged to form an upwardlyfacing tapered annular load shoulder 166, having a taper of for instance45 degrees to the horizontal. Alternately, means such as the ports 42and retractable wedges 56, 58 of FIGURE 1 could be provided at thispoint to maximize the diameter of the bore 156. Upwardly of the shoulder166, the bore 156 includes a cylindrically curved region 168, arelatively steeper tapered, annular upwardly facing sealing surface .170corresponding to the surface 32 in FIGURE 1, an annular recess 172concentric with the bore 156, a cylindri-cally curved region 174, a moreshallow tapered, annular, upwardly facing sealing surface 176 relativeto the surface 170 and corresponding to the surface 26 of FIG- URE l, acylindrically curved region 178 and an upwardly facing, frusto-conicbonnet seat and sealing surface 1-80 adjacent and leading to the upperend of the bore 156.'

When the casing 182 is to be hung in the well, it is secured to a hanger184 similar to the hanger 64 of FIGURE 1 for instance by exteriorthreading 186 on the casing 182 leading to the upper end thereof andinterior threading 188 in the bore 190 adjacent and leading to the lowerend thereof.

The exterior of the hanger 184 includes a tapered annular seat 192complementary to the load shoulder 166 and first and second downwardlyfacing tapered annular sealing surfaces 194 and 196 respectivelycomplementary to the surfaces 170 and 176 of the casing head 158. Eachof the surfaces 194, 196 preferably has a pair of vertically spacedannular recesses 198 therein which receive conventional packing material200. The latter projects beyond the surfaces 194, 196 before seating ofthe hanger 184 but is compressed to flushness as shown upon seating. Anannular recess 202 is formed in the exterior of the hanger 184 betweenthe sealing surfaces 194 and 196. The recess 202 is positioned on thehanger to form, complementarily wit-h recess 172, a generally toroidalchamber 204, between the hanger 184 and head 158 when the hanger 184 isseated. The chamber 204 is preferably communicated at at least one point206 to the bore 190 of the hanger 184 and to the exterior of the head158, for instance by an annulus port 208 comprising an arrangementsimilar to the arrangement 54, 28, 80 of FIGURE 1.

The hanger 184 and casing 182 can be lowered to the position shownutilizing a conventional lowering nipple (not shown) removably securableto the hanger 184- for instance, to the threads 210 in the bore 198.Similarly to the procedure discussed in regard to the embodiment ofFIGURE 1, as the hanger 184 is lowered by virtue of the differentialtaper and placement of the sealing surfaces 194 and 196 a seal begins tobe made at first at 176, 196 and second at 170, 194 before the seat 192lands on the load shoulder. Also similarly, the seals 194, 196 and 170,194 are prestressed in the sense that they are sequentially set so thateach carry a predeterminable load resulting from the weight of thecasing 182 and hanger 184 to the casing head .158. According to thepresent invention because of the prestressed seal above and below thechamber 204, the likelihood of extremely high subterranean pressurecommunicated to the interior of the casing 182 leaking upwardly ordownwardly from the chamber 204 rather than being controllable from theannulus port arrangement 206, 208 is greatly reduced.

A further casing 212 can be received in the well and hung via a hangerassembly 214 similar to the hanger assembly 130. The lower hangerelement 216 of the assembly 214 is shown gripping the exterior of thecasing 212 and being seated on an upwardly facing, tapered annular loadshoulder 218. The provision of the seals 176, 196 and 170, 194 ensuresthat a predeterminable portion of the load resulting from the weight ofthe casing 212 and lower hanger element 216 will be transferred throughthe hanger 182 directly to the casing 158 adjacent these seals ratherthan being fully incumbent upon the load shoulder 166.

An upper hanger element or bonnet 220 similar to the bonnet 138 issealed and secured to the casing 212 above the element 216 and is seatedvia a downwardly facing frusto-conic shoulder 222, on the seat 180. Theupwardly facing tapered annular surface 224 on the bonnet 220 issealingly received against a complementary tapered annular surface 224in the throughbore 228 of a conventional tubing head 230 or the likesecured to the head 158 by a bolted flange arrangement 232 or the like.Additional hold down means such as a plurality of latch screws 234 areshown received in arcuately spaced laterally extending openings 236 in.the head 158. The inner ends of the lower row of screws 234 engage anouter, upwardly facing tapered annular surface 238 leading from theupper extent of the hanger 184. The inner ends of the upper row ofscrews 234 are received in an annular groove in the exterior of thebonnet 220. These hold down means 234 are of special aid in preservingcontrol of the well at the time the blowout preventer stack is beingremoved from the head 158 preparatory to the mounting of the head 230thereon. Numerals 242 indicate conventional test ports.

The well head shown in FIGURE 2 may be further completed by theinstallation of production equipment such as tubing, valving, Christmastree cap, Christmas tree and the like.

By way of example, the program of casing shown in FIGURE 2 may include a20 inch O.D. casing 126, a 13% inch O.D. casing 128, a 9 inch O.D.casing 182 and a 5 inch O.D. casing 212, the latter two being sustainedin the head 158 by the hanger 184.

The embodiment shown in FIGURE 3 is in most respects identical to thatshown in FIGURE 2 and is similarly numeraled. The major differencebetween the two is that in the program of FIGURE 3, the casing 212 isused as a liner and is not brought to the surface. It is not shown inFIGURE 3. Instead of the casing hanger 214, of FIGURE 2, the hanger 184in an inner, upwardly facing tapered annular seat 244 leading to theupper end thereof supportingly and sealingly receives a tubing hanger246 held thereagainst by the upper row of latch screws 234.

9 The tubing hanger supportingly receives a string of tubing 248 forinstance by the tightening of the gland 250 which flexes the V-rings 252into sealing engagement with the tubing exterior and the threadedsecurement of a special bushing 254 at its upper end to the tubing head256 and at its lower end to the upper end of the tubing.

The manner of effecting this exemplary completion ismore fully set forthin the US. patent to Yancey, 2,241,- 288, granted May 6, 1941.

Of course, the completion having a single tubing shown in FIGURE 3 couldbe modified to include a plurality of tubing strings as is known in theart.

From the foregoing detailed explanation relating to exemplaryembodiments of the invention, it should be clear that the inventiondisclosed efiiciently accomplishes each of the objects set forth at theoutset of the specification. It should be apparent that the specificembodiments shown can be considerably modified Within the purview of theinventions principles and therefore, the invention should be understoodas encompassing all such modifications as are within the spirit andscope of the following claims.

I claim:

1. A well head assembly including a housing having means defining alongitudinal throughbore therein; means defining a lateral outlet insaid housing communicating with the throughbore intermediate the endsthereof; means defining a first upwardly facing shoulder in saidthroughbore above the juncture of said outlet therewith; means defininga second upwardly facing shoulder in said throughbore below the junctureof said outlet therewith; a hanger received in said housing throughboreand at least partially supported on said first and second shoulders,said shoulders being so spaced and configured that said hanger begins toengage said first shoulder before engaging said second shoulder as saidhanger is received in said throughbore whereby a predeterminable portionof the load resulting from the weight of the hanger is transferred tothe housing at said first shoulder.

2. A well head assembly as set forth in claim 1 including primary loadshoulder means in said housing below said second shoulder for supportingthe majority of the weight of said hanger.

3. A well head assembly as set forth in claim 2 wherein the primary loadshoulder means comprises a side outlet communicating with saidthroughbore and means received in said side outlet and advanceabletherein into constricting relationship with said throughbore.

4. A well head assembly as set forth in claim 3 wherein said first andsecond upwardly facing shoulders comprise first and second taperedannular surfaces concentric with the housing throughbore, the firsttapered annular surface being tapered at a more acute angle with respectto the longitudinal axis of the housing throughbore than the secondtapered annular surface.

5. A well head assembly as set forth in claim 4 wherein said secondtapered annular surface is spaced above the means received in said sideoutlet sufiiciently that as said hanger is being received in saidhousing said hanger begins to seat first on said first tapered annularsurface above said lateral outlet and second on said second taperedannular surface below said lateral outlet before seating on the meansreceived in said side outlet.

6. A well head assembly as set forth in claim 5 wherein said hangerincludes three downwardly facing, vertically spaced annular surfaces theuppermost and intermediate of which are respectively taperedcorrespondingly to the first and second tapered annular surfaces of saidhousing; said three hanger surfaces being received abuttingly adjacentsaid housing first and second tapered annular surfaces and the meansreceived in said side outlet to support said hanger in said housing.

7. A well head assembly as set forth in claim 6 further includingannular resilient sealing means received between said housing firsttapered annular surface and the uppermost of said hanger annularsurfaces and at least one annular resilient sealing ring receivedbetween said housing second tapered annular surface and the intermediateof said hanger annular surfaces for providing a preloaded seal above andbelow said lateral outlet.

8. A well head assembly as set forth in claim 7 further including meansdefining a throughbore in the hanger and means defining a lateralopening in the hanger communicating with the throughbore thereof andwith the housing lateral outlet.

9. A well head assembly as set forth in claim 2 wherein the primary loadshoulder means comprises an upwardly facing tapered annular surfaceconcentric with said throughbore.

10. A well head assembly as set forth in claim 9 wherein said first andsecond upwardly facing shoulders comprise first and second taperedannular surfaces concentric with .said throughbore, the first taperedannular surface being tapered at a more acute angle with respect to thelongitudinal axis of the throughbore than the second tapered annularsurface.

11. A well head assembly as set forth in claim 10 wherein said secondtapered annular surface is tapered at a more acute angle with respect tothe longitudinal axis of the throughbore than said primary load shoulderwhereby as said hanger is being received in said housing said hangerbegins to seat first on said first tapered annular surface above saidlateral outlet and second on said second tapered annular surface belowsaid lateral outlet before seating on said primary load shoulder.

12. A well head assembly as set forth in claim 11 wherein said hangerincludes three downwardly facing vertically spaced tapered annularsurfaces respectively tapered correspondingly to the first and secondtapered annular surfaces and primary load shoulder of said housing, saidthree hanger surfaces being received abuttingly adjacent said housingfirst and second tapered annular surfaces and primary load shoulder tosupport said hanger in said housing.

13. A well head assembly as set forth in claim 12 further includingannular resilient sealing means received between said housing firsttapered annular surface and the uppermost of said hanger three taperedannular surfaces and at least one annular resilient sealing ringreceived between said housing second tapered annular surface and theintermediate of said hanger three tapered annular surfaces for providinga preloaded seal above and below said lateral outlet.

14. A well head assembly as set forth in claim 13 further includingmeans defining annular grooves in said hanger uppermost and intermediatetapered annular surfaces, said annular resilient sealing means beingreceived in said grooves.

15. A well head assembly as set forth in claim 13 further comprising athroughbore in said hanger; a first larger diameter conduit string;means supporting said first conduit string adjacent the upper end ofsaid first conduit string in said hanger throughbore, a second smallerdiameter conduit string received in said hanger throughbore and withinsaid first conduit string; and means supporting said second conduitstring adjacent the upper end of said second conduit string in saidhanger throughbore.

16. A well head assembly as set forth in claim 15 wherein said first andsecond conduit strings comprise well casing and the means supporting thesecond casing includes means defining an upwardly facing annularshoulder in said hanger throughbore and a casing hanger supportinglyreceived on the last-mentioned shoulder and secured to the secondcasing.

17. A well head assembly as set forth in claim 15 wherein the firstconduit string comprises well casing and said second conduit stringcomprises well tubing, and wherein the means supporting the well tubingincludes means defining an upwardly facing annular shoulder in saidhanger throughbore and a tubing hanger supportingly received on thelast-mentioned shoulder and secured to thewell tubing 18. A well headassembly as set forth in claim 15 further comprising means defining alateral opening in said hanger communicating with said hangerthroughbore and the exterior of said hanger; and means communicating thehanger lateral opening with the lateral port in said housing forproviding communication between the annulus defined between the firstand second conduit strings and the exterior of said housing.

'19. A Well head assembly as set forth in claim 18 wherein saidcommunicating means comprises a circumferential groove in the exteriorof said hanger and intersecting the opening therethrough, and acircumferential groove in the throughbore of said housing intersectingthe juncture of the lateral port therewith; said circumferential groovesbeing positioned radially adjacent one another to define a generallytoroidal chamber.

References (Iited by the Examiner UNITED STATES PATENTS Howard 285143Penick et al. 2774 Shaffer et a1. 285-143 X McDonough et al. 16689 XLemley 16688 Baker et al. 285142 X Raulins et al. 166-89 Peterson 16688Rector 285137 Great Britain,

CHARLES E. OCONNELL, Primary Examiner.

I. A. CALVERT, Assistant Examiner.

1. A WELL HEAD ASSEMBLY INCLUDING A HOUSING HAVING MEANS DEFINING ALONGITUDINAL THROUGHBORE THEREIN; MEANS DEFINING A LATERAL OUTLET INSAID HOUSING COMMUNICATING WITH THE THROUGHBORE INTERMEDIATE THE ENDSTHEREOF; MEANS DEFINING A FIRST UPWARDLY FACING SHOULDER IN SAIDTHROUGHBORE ABOVE THE JUNCTURE OF SAID OUTLET THEREWITH; MEANS DEFININGA SECOND UPWARDLY FACING SHOULDER IN SAID THROUGHBORE BELOW THE JUNCTUREOF SAID OUTLET THEREWITH; A HANGER RECEIVED IN SAID HOUSING THROUGHBOREAND AT LEAST PARTIALLY SUPPORTED ON SAID FIRST AND SECOND SHOULDERS,SAID SHOULDERS BEING SO SPACED AND CONFIGURED THAT SAID HANGER BEGINS TOENGAGE SAID FIRST SHOULDER BEFORE ENGAGING SAID SECOND SHOULDER AS SAIDHANGER IS RECEIVED IN SAID THROUGHBORE WHEREBY A PREDETERMINABLE PORTIONOF THE LOAD RESULTING FROM THE WEIGHT OF THE HANGER IS TRANSFERRED TOTHE HOUSING AT SAID FIRST SHOULDER.